# Function index Create an index. An Index can store ranges having start, step, and end for multiple dimensions. Matrix.get, Matrix.set, and math.subset accept an Index as input. ## Syntax ```js math.index(range1, range2, ...) ``` ### Where - A number - A string for getting/setting an object property - An instance of `Range` - A one-dimensional Array or a Matrix with numbers ### Parameters Parameter | Type | Description --------- | ---- | ----------- `ranges` | ...* | Zero or more ranges or numbers. ### Returns Type | Description ---- | ----------- Index | Returns the created index ## Examples ```js const b = [1, 2, 3, 4, 5] math.subset(b, math.index([1, 2, 3])) // returns [2, 3, 4] const a = math.matrix([[1, 2], [3, 4]]) a.subset(math.index(0, 1)) // returns 2 ``` ## See also [bignumber](bignumber.md), [boolean](boolean.md), [complex](complex.md), [matrix](matrix.md), [number](number.md), [string](string.md), [unit](unit.md)